Electrical service providers such as electrical utilities employ electricity meters to monitor energy consumption by customers (or other entities). Electricity meters track the amount of energy consumed by a load (e.g. the customer), typically measured in kilowatt-hours (“kwh”), at each customer's facility. The service provider uses the consumption information primarily for billing, but also for resource allocation forecasting and other purposes.
Electricity meter tampering is a form of energy theft that can have significant impact on costs for utilities and paying customers. Electricity meter tampering typically involves modification of the meter to bypass, alter or disconnect the consumption metering function of the meter, such that less than all of the actual energy consumption is registered.
An emerging type of meter tampering involves the use of a high power magnet. In particular, electricity meters using standard current transformers (“CTs”) are susceptible to tampering using high-power magnetics. To this end, the CT current sensor behavior can be impacted if a large magnet such as a neodymium iron boron magnet (sometimes referred to as a rare earth magnet) is placed in close proximity. The high intensity magnetic field will result in an error in sensing current and potentially a significant under-registration of (and consequent underbilling for) energy consumed.
To combat this issue, it has been known to place a ferromagnetic shielding structure around the CT or the entire interior of the meter to reduce the impact of the magnetic field on interior components. However, magnetic shielding requires additional material and labor cost, and undesirably increases the weight of the meter.
It is also known to employ a sensor to detect and flag a potential tampering situation. See U.S. Patent Publication No. 2010/0072990 and U.S. Pat. No. 7,495,555 for examples of this method. However, even when tampering is detected and flagged, some revenue loss nevertheless occurs due to either delay in fixing the tampering situation. Even if service is immediately disconnected from the load, there is lost revenue.
There is a need, therefore, for a more cost-effective approach to combating this type of meter tampering that further reduces the revenue lost due to tampering.